Current antimicrobial paradigms, such as antibiotics, broadly target microbial processes and cannot be specifically targeted against virulence factors or antibiotic-resistance genes, resulting in selection and dissemination of resistance among virulent and non-virulent organisms. Thus, this paradigm is always playing catch-up, as microbial consortia constantly trade and evolve traits to resist sporadic broad-spectrum treatments. As antibiotic resistance continues to spread and multidrug resistant strains continue to emerge, the production of novel antibiotic compounds remains behind.
Recent efforts to compensate for the lag in antibiotic production are directed to synthetic bacterial systems that rely on signal detection of pathogens and respond by producing antimicrobial agents (e.g., quorum-signaling molecules or pyocins). These current synthetic systems cannot directly target existing and emerging virulence factors or antibiotic resistance genes and, thus, are not useful for combating, for example, recombinant biothreat genes (e.g., genes that, when expressed, may be harmful), which may be engineered to be expressed by otherwise innocuous organisms such as probiotic strains of bacteria.